Endless tracks have been used for many years with vehicles such as tanks to facilitate off-the-road travel. A pair of such tracks are conventionally utilized with each vehicle at each of its lateral sides. An outwardly facing side of each track engages the ground while an inwardly facing side of the track engages an associated set of roadwheels on the vehicle and a drive sprocket, a compensating idler wheel, and support rollers along an upper reach of the track above the roadwheels. The constantly increasing weight and speed of track laying vehicles has resulted in a decrease in the track life and a constant increasing need for track maintenance by either repair or replacement. However, conventional endless tracks are not designed to facilitate track maintenance in the field as would most desirably be the case.
The conventional construction of an endless track for a track laying vehicle includes shoe assemblies which are connected along the length of the track with each shoe assembly including a pair of laterally spaced track shoes connected by an associated pair of pins. Each shoe assembly conventionally has a metal shoe housing on which an outwardly facing road pad and an inwardly facing roadwheel pad are mounted. While roadwheel pads do not normally wear significantly, road pads normally do not last more than 800 to 1000 miles. One particular problem is road pad chunking that results from the heat produced with higher speeds and greater weights of present day tanks. Prior attempts to improve track designs have included stamped housing members such as shown by U.S. Pat. Nos. 1,313,266 Couch; 2,301,954 Knox; 2,327,909 Krotz; 2,353,123 Burgess; and 2,548,626 Sinclair. However, the stamped housings disclosed by these prior references have not received any significant commercial acceptance.
To facilitate track maintenance, road pads of track shoes have previously been replaceable. Such replacement is usually achieved by use of a threaded connection that can loosen during use. Replaceable road pads utilizing threaded connections are illustrated by U.S. Pat. Nos. 2,332,976 Saurer et al; 3,357,750 Reynolds et al; and 4,262,972 Falk. U.S. Pat. No. 2,353,124 Burgess discloses a track shoe in which the road pad is secured by rivets which would eliminate the loosening problem present with threaded connections; however, such rivets make replacement of the road pad more difficult so that the replacement cannot be performed as a field maintenance operation. Likewise, U.S. Pat. No. 4,139,241 Huhne et al discloses a track shoe wherein deformation of the resilient pad allows insertion of retainer elements into claw-like projections; however, the assembly device utilized to perform the pad deformation also inhibits the replacement of the road pad as a field maintenance operation.
Laterally aligned track shoes are conventionally connected by a pair of pin assemblies that extend through the housings of the shoes. These pin assemblies conventionally each include an outer sleeve that includes a pair of sleeve portions respectively located within the housings of the two shoes connected by the pin assembly. Each pin assembly also includes a pin that extends through both sleeve portions and rubber bushings that are interposed between the pin and the sleeve portions by compression upon insertion of the pin into the sleeve portions. Such compression must be sufficient so that there is no rotation between the bushing and the outer sleeve portions or the pin upon bending of the track during use. However, such compression of the bushing results in a greater resistance to the required bending during use and a consequent greater power requirement for driving of the associated vehicle. Conventional pin assemblies incorporating compressed bushings are disclosed by U.S. Pat. Nos. 1,973,214 Lamb; 2,089,210 Knox et al; 2,301,954 Knox; 2,332,976 Saurer et al; 3,357,750 Reynolds et al; 4,139,241 Huhne et al; and 4,195,887 Ruddell.
Hollow pins have previously been utilized with vehicle tracks to reduce the track weight. See for example U.S. Pat. Nos. 1,863,858 Knox; 1,973,214 Lamb; 3,762,778 Boggs et al; 3,948,574 Baller; 4,120,537 Roley et al; 4,126,359 Holze; 4,163,589 Fox et al; 4,195,887 Ruddell; 4,265,084 Livesay; 4,288,172 Livesay et al; 4,324,437 Narang; and 4,395,074 Haldimann et al. However, such hollow pins reduce the strength of the ends of the pins where end connectors are secured to provide connection between adjacent shoe assemblies of the track and, as such, present a strength problem.
To provide guiding of vehicle tracks, each shoe assembly of conventional tracks includes a center guide that projects in an inward direction to be received within a center slot in the roadwheels. These center guides are conventionally designed to clamp onto central portions of adjacent pins of adjacent shoe assemblies to cooperate with the pin end connectors in securing the shoe assemblies to each other. The center guides are conventionally clamped to the pins by threaded connections that have the same loosening problem involved with conventional replaceable road pads as discussed above. Such prior center guides for vehicle tracks are disclosed by U.S. Pat. Nos. 2,089,210 Knox et al; 2,283,936 Knox; 2,301,954 Knox; 2,332,976 Saurer et al; 3,357,750 Reynolds et al; 3,467,446 Seelbach et al; 3,582,156 Korner et al; 4,139,241 Huhne et al; and 4,262,972 Falk.
As mentioned above, adjacent shoe assemblies are conventionally connected by end connectors that extend between the adjacent pin ends. These end connectors conventionally include a wedge connection that is secured by a threaded bolt and/or nut. Such threaded fastening of the wedge connector can loosen during use and requires a greater amount of time for installation and removal than is desirable. Prior end connectors for vehicle tracks are disclosed by U.S. Pat. Nos. 1,028,893 Luther; 1,282,326 Turnbull; 1,446,870 Borst, Jr.; 1,913,098 Alden; 2,957,731 Backhaus; 3,032,376 Blazek et al; 3,056,309 Horste; 3,467,446 Seelbach et al; 4,175,798 Korner et al; and 4,262,973 Grilli et al.
Between the opposite pin ends, adjacent track shoes of vehicle tracks are conventionally connected by the clamping of the center guides extending between intermediate portions of the adjacent pins as mentioned above at a location laterally between the shoes of the track. The dual function of guiding and connecting the adjacent pins results in a substantial loading during use. Usually, the center guide clamps onto each intermediate pin portion with two lines of contact that results in "reseating" due to the substantial loading involved during use. Such reseating can ultimately produce wear that losens the center connection between the pins and the resultant useful lifetime of the track.